CN205657592U - Single switch tube of three winding coupling inductance double -pressure direct -current converter that steps up - Google Patents

Abstract

The utility model discloses a three-winding coupled inductance doubler type single switch tube step-up DC converter, which belongs to the technical field of power electronic converters. The converter includes: a drive unit, a first voltage doubler unit, a second voltage doubler unit, and an output unit. The drive unit, the first voltage doubler unit, and the second voltage doubler unit share a switch tube, which simplifies control and improves the power of the converter. Density, high voltage gain is achieved with a small duty cycle and coupling inductor turn ratio, expanding the application range of the converter.

Description

A Three-Winding Coupled Inductor Voltage Doubler Single-Switch Boost DC Converter

technical field

The invention discloses a three-winding coupled inductance voltage doubler single switch tube step-up direct current converter, in particular a step-up direct current converter suitable for high voltage gain occasions, belonging to the technical field of power electronic converters.

Background technique

In new energy power generation systems such as uninterruptible power supply (UPS, Uninterruptible Power Supply) system, high-pressure gas discharge lamp (HID, High Intensity Discharge) system, fuel cell and solar cell, it is necessary to convert the lower DC voltage into a higher DC voltage. voltage for use. In theory, the traditional boost converter can use the limit duty cycle to obtain a large voltage gain. However, in practical applications, due to the influence of device parasitic parameters, when a large duty cycle (greater than 0.8) is used, its conversion Efficiency is greatly reduced. Typical forward and flyback converters can achieve high voltage gain by adjusting the turn ratio, but the magnetic flux leakage of the transformer will cause a large voltage spike when the switch is turned off, and the magnetic flux leakage energy is not effectively utilized. Therefore, both the traditional boost converter and the typical forward and flyback converter are not suitable for low-voltage input and high-voltage output applications with high gain requirements.

In order to increase the gain of the boost converter, the patent application number 201310377481.3 discloses a two-winding coupled inductor voltage doubler single-switch high-gain converter. By cascading the coupled inductor voltage doubler unit after the traditional boost unit, the switch is suppressed. The voltage peak when the tube is turned off reduces the voltage stress on the switch tube, recovers the leakage inductance energy, and improves the voltage gain. The converter disclosed in this patent stores the energy of the DC power supply in the secondary winding and the second capacitor when the switch tube is turned on, and the electric energy stored in the secondary winding and the second capacitor supplies power to the load when the switch tube is turned off. It can be seen that , the DC power supply does not directly supply power to the load, and the power utilization rate is not high. Under the condition of certain turns ratio and duty ratio, the voltage gain is not large enough, and increasing the turns ratio will increase the volume and weight of the converter and make the linearity of the coupled inductance worse, and increasing the duty ratio will lead to conduction Loss increases. The leakage inductance energy of the primary side is only absorbed by the second capacitor connected to the secondary winding, and the second capacitor withstands a large current impact in a short time, which is not conducive to the reliable operation of the converter.

Contents of the invention

1. The technical problem to be solved by the invention

The object of the present invention is to address the shortcomings of the above-mentioned background technology, to provide a three-winding coupled inductor voltage doubler type single-switch step-up DC converter, which can achieve higher voltage gain with a smaller duty cycle and coupled inductor turn ratio, The invention solves the technical problems of insufficient voltage raising capability of the existing high-gain boost converter, low conversion efficiency of the converter, and poor operation reliability.

2. Technical solution

In order to solve the above problems, the technical solution provided by the invention is:

A three-winding coupled inductor voltage doubler type single-switch step-up DC converter, comprising: a drive unit, a first voltage doubler unit, a second voltage doubler unit and an output unit, wherein,

The drive unit includes: a first winding and a switch tube, the first terminal of the first winding is connected to the anode of the DC voltage source, the second terminal of the first winding is connected to the drain of the switch tube, and the source of the switch tube is connected to the DC voltage source source negative connection,

The first voltage doubler unit is a circuit formed by a branch circuit including the second winding and the switch tube, the second voltage doubler unit is a circuit formed by the branch circuit including the third winding and the switch tube, and the second winding and the switch tube are formed. The turns ratio of the first winding is the same as that of the third winding and the first winding,

Said output unit: its input terminal is connected with the branch circuit composed of the DC voltage source, the first winding, the second winding and the third winding, and the output terminal provides the boosted DC power to the load when the switching tube is turned off.

As a further optimization scheme of the three-winding coupled inductor voltage doubler type single-switch step-up DC converter:

In the first voltage doubler unit, the branch circuit containing the second winding includes: the second winding, the second capacitor, the third capacitor, and the second diode, and the first terminal of the second winding is connected to one pole of the second capacitor , the other pole of the second capacitor is connected to the drain of the switch tube, the source of the switch tube is connected to one pole of the third capacitor, the other pole of the third capacitor is connected to the anode of the second diode, and the cathode of the second diode is connected to the second The second terminals of the windings are connected, and the first terminals of the second winding and the first terminals of the first winding are terminals with the same name.

In the second voltage doubler unit, the branch circuit including the third winding includes: a third winding, a fourth capacitor, a first capacitor, and a fourth diode, and the first terminal of the third winding is connected to one pole of the fourth capacitor , the other pole of the fourth capacitor is connected to the source of the switch tube, the drain of the switch tube is connected to one pole of the first capacitor, the other pole of the first capacitor is connected to the cathode of the fourth diode, and the anode of the fourth diode is connected to the third The second terminals of the windings are connected, and the second terminals of the third winding and the first terminals of the first winding are terminals with the same name.

Still further, in the three-winding coupled inductor voltage doubler single-switch step-up DC converter, the first voltage doubler unit further includes a first diode, and the second voltage doubler unit further includes a third diode, The anode of the first diode is connected to the connection point of the drain of the switch tube, the cathode of the first diode and the anode of the second diode are connected to the connection point of the third capacitor, and the anode of the third diode is connected to the connection point of the drain of the switch tube. A capacitor is connected to the connection point of the cathode of the fourth diode, and the cathode of the third diode and the fourth capacitor are connected to the connection point of the source of the switch tube.

Furthermore, in the three-winding coupled inductor voltage doubler single-switch step-up DC converter, the output unit includes: an output diode, an output capacitor, the anode of the output diode and the second terminal of the second winding and the second diode The connection point of the cathode is connected, the cathode of the output diode is connected to one pole of the output capacitor, and the other pole of the output capacitor is connected to the connection point of the second terminal of the third winding and the anode of the fourth diode.

As a further optimization scheme of the three-winding coupled inductor voltage doubler single-switch step-up DC converter, the three-winding coupled inductor is connected to the three-winding ideal transformer, the leakage inductance converted to the primary side of the three-winding ideal transformer and connected in parallel The equivalent representation of the magnetizing inductance of the primary side.

3. Beneficial effect

Compared with the prior art, the technical solution provided by the invention has the following beneficial effects:

(1) Use the first winding of the three-winding coupled inductor and the switch tube to form the drive unit, and use the second winding, the third winding, capacitors, and diodes to form two symmetrical voltage doubler units, with a smaller duty cycle and coupling The inductance turns ratio achieves a higher voltage gain, the drive unit shares the ground with the two voltage doubler unit circuits and has only one switch tube, which simplifies the control and improves the power density of the converter;

(2) When the switch tube is turned off, the two voltage doubler units each form a branch circuit that absorbs the leakage inductance energy of the coupling inductor, which suppresses the voltage peak when the switch tube is turned off, reduces the voltage stress of the switch tube, and reduces the The voltage stress of other power devices improves the reliability of the converter;

(3) When the switching tube is turned off, the DC voltage source directly supplies power to the load through three windings, which improves the power conversion rate and further increases the gain;

(4) A small duty cycle can make the peak value of the input current low, the input current ripple small, and reduce the conduction loss at the same time. The small turn ratio avoids the problem of poor linearity caused by the high turn ratio of the magnetic core. Moreover, due to the effect of the coupled inductance, it not only increases the output voltage gain, but also alleviates the problem of diode reverse recovery and reduces loss.

Description of drawings

Fig. 1 is a topological structure diagram of the main circuit of the converter of the present invention.

Fig. 2 is a voltage/current waveform diagram of main components in one switching cycle of the converter of the present invention.

Figure 3(a) is one of the working mode diagrams of the converter.

Figure 3(b) is the second working mode diagram of the converter.

Figure 3(c) is the third working mode diagram of the converter.

Figure 3(d) is the fourth working mode diagram of the converter.

Figure 3(e) is the fifth working mode diagram of the converter.

Figure 3(f) is the sixth working mode diagram of the converter.

FIG. 4 is a graph showing the relationship between the voltage gain and the duty cycle of the converter of the present invention, the Flyback converter, and the converter disclosed in the aforementioned patents.

Explanation of symbols in the figure: V _in is a DC voltage source, N ₁ , N ₂ , and N ₃ are respectively the first winding, the second winding, and the third winding of the coupled inductor, 1 is the first terminal, 2 is the second terminal, L _m is the excitation inductance, L _k is the leakage inductance, S is the switching tube, C ₁ , C ₂ , C ₃ , and C ₄ are the first capacitor, the second capacitor, the third capacitor, and the fourth capacitor, respectively, D ₁ , D ₂ , D ₃ , D ₄ are the first diode, the second diode, the third diode, and the fourth diode respectively, D _o is the output diode, C _o is the output capacitor, R is the load, C _Do is the equivalent parallel capacitance of the output diode, and _CD2 and _CD4 are the equivalent parallel capacitance of the second diode and the fourth diode, respectively.

detailed description

In order to further understand the content of the present invention, the present invention will be described in detail in conjunction with the accompanying drawings and embodiments.

As shown in FIG. 1 , the converter disclosed in the present invention includes: a driving unit, a first voltage doubling unit, a second voltage doubling unit and an output unit.

The drive unit includes: _{a first} winding N1 and a switch tube S, the first terminal ₁ of the first winding N1 is connected to the positive pole of the DC voltage source V _in , the second terminal ₂ of the first winding N1 is connected to the drain of the switch tube S The two ends of the first winding N ₁ are connected in parallel with the excitation inductance L _m , and the source of the switching tube S is connected to the negative pole of the DC voltage source V _in .

The first voltage doubler unit is a circuit formed by a branch circuit containing the second winding N ₂ and a switch tube S. The branch circuit containing the second winding N ₂ includes: the second winding N ₂ , the second capacitor C ₂ , and the third capacitor C _3. The second diode D2, the first terminal ₁ of the second winding _N2 is connected to one pole of the _second capacitor C2, the other pole of the _second capacitor C2 is connected to the drain of the switching tube S, and the source of the switching tube S One pole of the _third capacitor C3 is connected to one pole, the other pole of the _third capacitor C3 is connected to the anode of the _second diode D2, and the cathode of the _second diode D2 is connected to the second terminal ₂ of the second winding N2 , the first terminal 1 of the second winding _N2 and the first terminal ₁ of the first winding N1 are terminals with the same name.

The second voltage doubler unit is a loop formed by a branch circuit containing the third winding N ₃ and a switch tube S, and the branch circuit containing the third winding N ₃ includes: the third winding N ₃ , the fourth capacitor C ₄ , the first capacitor C _1. The _fourth diode D4, the first terminal 1 of the _third winding N3 is connected to one pole of the fourth capacitor _C4 , the other pole of the fourth capacitor _C4 is connected to the source of the switching tube S, and the drain of the switching tube S One pole of the first capacitor _C1 is connected to one pole, the other pole of the first capacitor _C1 is connected to the cathode of the _fourth diode D4, and the anode of the _fourth diode D4 is connected to the second terminal 2 of the _third winding N3 , the second terminal 2 of the _third winding N3 and the first terminal ₁ of the first winding N1 are terminals with the same name. The turn ratio of the second winding _N2 to the _first winding N1 is the same as the turn ratio of the _third winding N3 to the _first winding N1, and the circuit structures of the first voltage doubler unit and the second voltage doubler unit are symmetrical.

The input end of the output unit is connected to the branch circuit composed of the DC voltage source V _in , the first winding N ₁ , the second winding N ₂ , and the third winding N ₃ , and the electric energy of the DC voltage source V _in is directly Supply load R. The output unit includes: an output diode D _o , an output capacitor C _o , the anode of the output diode D _o and the second terminal 2 of the second winding N ₂ are connected to the connection point of the cathode of the second diode D ₂ , and the cathode of the output diode D _o is connected to One pole of the output capacitor C _o , the other pole of the output capacitor C _o are connected to the connection point between the second terminal 2 of the _third winding N3 and the anode of the _fourth diode D4.

The three-winding coupled inductance is equivalently represented by the three-winding ideal transformer, the leakage inductance L _k converted to the primary side of the three-winding ideal transformer, and the excitation inductance L _m paralleled to the primary side.

The voltage/current waveform diagram of the main components of the converter shown in Figure 1 in one switching cycle is shown in Figure 2, the driving voltage V _gs of the switching tube S, the current i _Lm of the exciting inductance L _m , and the current i of the leakage inductance L _{k Lk} , the current i _{N2 of the second winding N2 ,} the current i N3 of the _third winding _N3 , the current i _ds of the switching tube S, the current i D1 of the _first diode D1, the current i _D1 of the _second diode D2 Waveforms of the current i _D2 , the current i _D3 of the third diode D ₃ , the current i _D4 of the fourth diode D ₄ and the current i _Do of the output diode D _o in one switching period.

Figure 3(a) to Figure 3(f) show the different working modes of the converter shown in Figure 1 in one switching cycle, and the specific conditions are as follows:

1) Mode 1[t ₀ , t ₁ ]: The driving voltage V _gs of the switching tube S changes from low level to high level, the switching tube S is turned on, and the excitation inductance L _m continues to provide the load through the secondary side of the coupled inductance Energy, the current i _{N2 of the second winding N2 and} the current i _N3 of the _third winding N3 decrease rapidly, the leakage current i _Lk increases linearly, and the current i _ds of the switch tube S increases linearly. The current flow path is shown in Figure 3(a). When the current i _{N2 of the second winding N2 and} the current i N3 of the _third winding _N3 decrease to zero, the output diode D _o is turned off, and the mode ends.

2) Mode 2[t ₁ ,t ₂ ]: At t=t ₁ , the currents of the second winding N ₂ and the third winding N ₃ decrease to zero, and the equivalent parallel capacitance C _Do of the output diode D _o starts The energy is released to the leakage inductance L _k , the reverse recovery energy of the output diode D _o is stored in the leakage inductance L _k , the current i _N2 of the second winding N ₂ and the current i _N3 of the third winding N ₃ start to increase in reverse, and the DC voltage The source V _in begins to charge the excitation inductance L _m , and the current flow path is shown in Figure 3(b); when t=t ₂ , the reverse recovery energy of the output diode Do is completely absorbed by the leakage inductance L _k , and the mode ends .

3) Mode 3[t ₂ ,t ₃ ]: The switch tube S remains on, the current flow path is shown in Figure 3(c), the DC voltage source V _in continues to charge the excitation inductance L _m , the second diode D ₂ and the fourth diode D ₄ are turned on due to the forward voltage drop, the leakage inductance current i _Lk , the current i _N2 of the second winding N ₂ , the current i _N3 of the third winding N ₃ and the current i _ds of the switching tube S The characteristic increases, the second winding _N2 and the _third capacitor C3 discharge to the _second capacitor C2, the _third winding N3 and the first capacitor _C1 discharge to the fourth capacitor _C4 , when t= _t3 , the switching tube S off, the mode ends.

4) Mode 4[t ₃ ,t ₄ ]: The driving voltage V _gs of the switch tube S changes from high level to low level, the switch tube S is turned off, and the current flow path is shown in Figure 3(d). The current i _N2 of the second winding N ₂ and the current i _N3 of the third winding N ₃ decrease rapidly, the leakage current i _Lk decreases linearly, the second diode D ₂ and the fourth diode D ₄ are still conducting, the first _The diode D1 and the third diode _D3 bear the forward voltage drop and start conducting, the leakage inductance energy is recovered to the capacitor, when the current of the second winding _N2 and the _third winding N3 decreases to zero The _second diode D2 and the _fourth diode D4 are turned off and the mode ends.

5) Mode 5[t ₄ , t ₅ ]: The equivalent parallel capacitance _CD2 and CD4 of the second diode D2 and the fourth diode _D4 release energy to the leakage inductance L _k , and the current of the second winding N ₂ i _N2 and the current i _N3 of the _third winding N3 start to increase in the opposite direction, and the current flow path is shown in Figure ₃ (e). When t=t5, the reverse recovery energy of the diode is completely recovered, and the mode ends.

6) Mode 4[t ₅ ,t ₆ ]: The switch tube S remains off, the current flow path is shown in Figure 3(f), and part of the energy of the exciting inductance L _m and leakage inductance L _k is transferred to the first capacitor C ₁ and the third capacitor C ₃ are charged, the leakage inductance current i _Lk decreases linearly, the output diode D _o conducts due to the forward voltage drop, the DC voltage source V _in , the first winding N ₁ , the second winding N ₂ , the third The winding N ₃ , the second capacitor C ₂ and the fourth capacitor C ₄ are connected in series to discharge to the load R, the current i _N2 of the second winding N ₂ and the current i _N3 of the third winding N ₃ increase linearly and flow through the first diode The currents _of D1 and the _third diode D3 decrease linearly, and when the switch tube S is turned on again, the mode ends.

The steady-state gain of the converter shown in Figure 1 and the voltage stress of the power device are analyzed below.

In order to simplify the analysis process, the modes with extremely short time are ignored, and only modes 3 and 6 are analyzed. and make the following assumptions:

1. The first to fourth capacitors C ₁ , C ₂ , C ₃ , C ₄ and the output capacitor C _o are large enough, so the voltages V _C1 , V _C2 , V _C3 , V _C4 , and V _Co at both ends of each capacitor are in a switch remain unchanged throughout the cycle;

2. The power devices are all ideal devices, ignoring the influence of device parasitic parameters;

3. The coupling coefficient k=L _m /(L _m +L _k ) of the three-winding coupled inductor, and the turn ratio n=N ₂ /N ₁ =N ₃ /N ₁ .

When the switch tube S is turned on, according to mode 3, there are:

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; kV</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}^{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; nv</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; wxya</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In the formula, k is the coupling coefficient of the three-winding coupled inductor, and n is the turn ratio of the coupled inductor. This topology is symmetrical, and the number of turns of the second winding N ₂ and the third winding N ₃ are the same.

In the turn-off stage of the switch tube S, by applying the volt-second balance principle to the windings and leakage inductance of the coupled inductor, it can be known that:

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

It can be known from the above formula:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}^{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

According to (4)(5)(6) and (8), the output voltage can be expressed as:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}^{\mathrm{<span\; class="notranslate">\; V</span>}\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

So the voltage gain is:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

When ignoring the leakage inductance k=1, the voltage gain at this time is:

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}}{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

The voltage stress of the switch tube S:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; )</span>$

Diodes (D ₁ , D ₂ , D ₃ , D ₄ ) are subjected to voltage stress:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 13</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 14</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; o</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; )</span>$

Usually, the steady-state gains of traditional DC-DC boost converters, such as basic boost converters and Flyback converters, are 1/1-D and nD/1-D. The gain of the converter disclosed in the patent application number 201310377481.3 is n+1/1-D, when n=2, its gain is 3/1-D, and the number of turns of the primary side and the total number of turns of the secondary side are the same as the above patent In this case, that is, when the turn ratios of the second winding _N2 and the _third winding N3 to the first winding N1 are all ₁ , the gain of the converter disclosed in this patent is 5/1-D. It can be seen that the patent of the present invention proposes The converter can achieve the same gain with a smaller duty cycle, which is beneficial to reduce the conduction loss and improve the efficiency of the converter.

Fig. 4 shows the comparison of the steady-state gain between the present invention and the Flyback converter and the converter disclosed in the patent application number 201310377481.3 when the ratio of the total turns of the secondary side to the number of turns of the primary side is n=2. It can be seen that the steady-state gain of the patent of the present invention is much higher than that of the other two converters.

The embodiments described above are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Therefore, all changes made according to the shape and principle of the present invention should be covered by the protection scope of the present invention.

Claims (5)

1. A three-winding coupled inductor voltage doubler single switching tube step-up DC converter, characterized in that it comprises: a drive unit, a first voltage doubler unit, a second voltage doubler unit and an output unit, wherein, The drive unit includes: a first winding and a switch tube, the first terminal of the first winding is connected to the anode of the DC voltage source, the second terminal of the first winding is connected to the drain of the switch tube, and the source of the switch tube is connected to the DC voltage source source negative connection, The first voltage doubler unit is a circuit formed by a branch circuit including the second winding and the switch tube, the second voltage doubler unit is a circuit formed by the branch circuit including the third winding and the switch tube, and the second winding and the switch tube are formed. The turns ratio of the first winding is the same as that of the third winding and the first winding, Said output unit: its input terminal is connected with the branch circuit composed of the DC voltage source, the first winding, the second winding and the third winding, and the output terminal provides the boosted DC power to the load when the switching tube is turned off. 2. A three-winding coupled inductance voltage doubler type single-switch step-up DC converter according to claim 1, characterized in that, in the first voltage doubler unit, the branch circuit containing the second winding comprises: the second A winding, a second capacitor, a third capacitor, and a second diode, the first terminal of the second winding is connected to one pole of the second capacitor, the other pole of the second capacitor is connected to the drain of the switch tube, and the source of the switch tube One pole of the third capacitor is connected, the other pole of the third capacitor is connected to the anode of the second diode, the cathode of the second diode is connected to the second terminal of the second winding, the first terminal of the second winding and the first winding The first terminals of each have the same name. In the second voltage doubler unit, the branch circuit containing the third winding includes: the third winding, the fourth capacitor, the first capacitor, and the fourth diode. The third winding The first terminal of the first terminal is connected to one pole of the fourth capacitor, the other pole of the fourth capacitor is connected to the source of the switch tube, the drain of the switch tube is connected to one pole of the first capacitor, and the other pole of the first capacitor is connected to the cathode of the fourth diode connected, the anode of the fourth diode is connected to the second terminal of the third winding, and the second terminal of the third winding and the first terminal of the first winding are terminals with the same name. 3. A three-winding coupled inductance voltage doubler type single-switch step-up DC converter according to claim 2, wherein the first voltage doubler unit also includes a first diode, and the second doubler The voltage unit also includes a third diode, the connection point between the anode of the first diode and the second capacitor is connected to the drain of the switch tube, and the connection point between the cathode of the first diode and the anode of the second diode and the third capacitor The anode of the third diode and the first capacitor are connected to the connection point of the cathode of the fourth diode, and the cathode of the third diode and the fourth capacitor are connected to the connection point of the source of the switch tube. 4. According to claim 2 or 3, a three-winding coupled inductor voltage doubler type single-switch step-up DC converter is characterized in that the output unit includes: an output diode, an output capacitor, and the anode of the output diode and The second terminal of the second winding is connected to the connection point of the cathode of the second diode, the cathode of the output diode is connected to one pole of the output capacitor, and the other pole of the output capacitor is connected to the connection point of the second terminal of the third winding and the anode of the fourth diode . 5. A kind of three-winding coupled inductor voltage doubler type single-switch step-up DC converter according to claim 1, characterized in that, the three-winding coupled inductor is converted from the three-winding ideal transformer to the primary side of the three-winding ideal transformer The leakage inductance and the magnetizing inductance connected to the primary side are equivalently represented.